Uber, a start-up based in San Francisco, has won a following among urbanites with its novel twist on calling a car service: its app lets you summon a luxury sedan with a tap on your phone. Now it is trying to appeal to the less affluent by adding less luxurious cars.

In San Francisco and New York on Wednesday, Uber will start to give customers the option of choosing a hybrid car at a price that it says will be 10 to 25 percent more than a taxi. That compares with the 40 to 100 percent premium that customers pay for a black town car.

Having subsisted upon Uber’s existing service for the entirety of my trip to San Francisco, the addition of a slightly more affordable (and eco-friendly) tier makes plenty of sense. At the same time, I certainly hope such an expansion does not serve to undermine the unilateral quality of the Uber service.